Purification and characterization of ostrich prothrombin

The work focused on the penultimate enzyme, prothrombin, in the coagulation cascade. Prothrombin was purified and characterized from ostrich plasma. The results obtained contribute to a better understanding of blood coagulation in the ostrich and the evolution of prothrombin and the coagulation cascade. Prothrombin was purified from ostrich plasma by barium chloride precipitation, ammonium sulfate fractionation, and DEAE-cellulose and Cu(2+)-chelate Sepharose chromatography. Ostrich prothrombin exhibited a M(r) of 72,800 and a pI of 6.9 using SDS-PAGE and PAG-isoelectrofocusing, respectively. The N-terminal sequence of ostrich prothrombin showed 78 and 87% identity with human and bovine, respectively. The cDNA was isolated from ostrich liver and the predicted amino acid sequence compared with those from other species. Ostrich prothrombin shares sequence identity with chicken (84%), human (60%), bovine (59%), rat (60%), mouse (59%) and hagfish (50%) prothrombin, suggesting a common function of prothrombin in these vertebrates. Amino acid sequence identities indicate that the thrombin beta-chain (62%) and the propeptide-Gla (75%) domains are the regions most constrained for the common functions of vertebrate prothrombins. Ostrich prothrombin, therefore, shows similarity in structure to other vertebrate prothrombins.     

Purification and primary structure of ostrich insulin

Insulin has been isolated from ostrich pancreas by a procedure of acid ethanol extraction, adsorption onto SP-Sephadex, gel permeation chromatography and HPLC. The primary structure of the ostrich insulin is identical to that reported for the chicken hormone. The isoelectric point as determined by polyacrylamide gel isoelectric focusing was significantly higher than that of the bovine hormone.     

Dangerous dive cycles and the proverbial ostrich

Data rarely are available to address the level of predation risk faced by diving animals in different parts of the water column. Consequently, most published research on diving behaviour implicitly assumes – like the proverbial ostrich – that 'unseen' predators are functionally unimportant. We argue that failure to consider diving in a predation risk framework may have precluded many insights into the ecology of aquatic foragers that breathe air. Using existing literature and a simple model, we suggest that fear from submerged predators in several systems might be influencing patch residence time, and therefore the duration of other dive cycle components. These analyses, along with an earlier model of predation risk faced by diving animals at the surface, suggest that dive cycle organisation can be modified to increase safety from predators, but only at the cost of reduced energy gain. Theoretical arguments presented here can seed hypotheses on factors contributing to population declines of diving species. For instance, adjustments to the dive cycle that reduce predation risk might be unaffordable if resources are scarce. Thus, if animals are to avoid imminent starvation or substantial loss of reproductive potential, resource declines might indirectly increase predation rates by limiting the extent to which dive cycles can deviate from those that would maximize energy gain. We hope that ideas presented in this paper stimulate other researchers to further develop theory and test predictions on how predation risk might influence diving behaviour and its ecological consequences.     

鸵鸟蛋皮串珠装饰品的发现与研究

鸵鸟蛋皮串珠从旧石器时代开始成为人类主要的装饰品类型之一,提供人类行为和认知发展方面的重要线索,至今仍广泛流行于非洲的狩猎采集者社会中,充当个人和群体间信息通讯的媒介。本文将从鸵鸟蛋皮的结构和种属鉴定入手,系统介绍旧石器时代鸵鸟蛋皮串珠的发现,及民族学记录中鸵鸟蛋皮串珠的制作与使用,并对20世纪以来有关鸵鸟蛋皮串珠的考古学研究作以概述,以期对我国考古学的相关研究提供有价值的信息与帮助。     

Purification and primary structure of ostrich pancreatic polypeptide

Pancreatic polypeptide has been isolated from ostrich pancreas by gel filtration, ion exchange chromatography and high pressure liquid chromatography. The ostrich peptide contains 36 amino acids and has an amino acid composition similar to pancreatic polypeptide of other avian species. The primary structure of ostrich pancreatic polypeptide differs from that of the chicken peptide only at residues 3 and 18 where the ostrich peptide contains an alanine and a valine residue compared to the serine and isoleucine residues found in those positions in the chicken peptide.     

Design and simulation analysis of a bionic ostrich robot

Biomechanics and Modeling in Mechanobiology - To look for the reason why the biped animal in nature can run with such high speed and to design a bionic biped prototype which can behave the high...     

The purification and characterisation of m-calpain from ostrich brain

Calpains are intracellular cysteine proteases activated in a Ca(2+)-dependent manner. The purpose of the present study was to investigate the physico-chemical and kinetic properties of ostrich brain m-calpain. m-Calpain was purified by successive chromatographic steps on Toyopearl-Super Q 650s and Pharmacia Mono Q HR 5/5 columns. A Ca(2+) concentration of 5mM and a casein concentration of 5mg/ml were found to be necessary for optimum calpain activity. Ostrich m-calpain exhibited a M(r) of 84K using SDS-PAGE and a M(min) of 79.3K from amino acid analysis. The pH and temperature optima were found to be 7.5 and 37 degrees C, respectively. The amino acid composition of m-calpain revealed 700 residues. The N-terminal sequence of m-calpain showed sequence identity with chicken (27%), human (23%) and rabbit (18%) and Schistoma mansoni (9%).     

Isolation and characterization of a neurophysin from ostrich neurohypophyses

A neurophysin has been isolated from ostrich neurohypophyses using acid acetone extraction, salt fractionation and Sephadex G-75 chromatography. The crude neurophysin eluting from the Sephadex G-75 column was subjected to a) reverse-phase HPLC followed by Sephadex G-75 chromatography, b) DEAE-Sephadex A-50 chromatography or c) isoelectric focusing. The different homogeneous ostrich neurophysin fractions so obtained were compared i.t.o. amino acid composition, spectral properties, N-terminal amino acid residues and PAGE. They all revealed a single N-terminal Ala residue and displayed spectral properties (A280/A260 less than 1) which are typical of mammalian neurophysin-like polypeptides. Ultracentrifugation studies on purified ostrich neurophysin over a range of concentrations revealed a reversible concentration dependent association behaviour characterized by the presence of dimeric complexes at higher concentrations. Partial sequencing from the N-terminus revealed the molecule to be VLDV-like. The purified molecule was also submitted to CNBr fragmentation.     

Mechanisms of action of ostrich beta-defensins against Escherichia coli

To understand their mechanism of antimicrobial activity against Gram-negative bacteria, ostrich beta-defensins, ostricacins-1 and 2 (Osp-1 and Osp-2), were compared with those of sheep myeloid antimicrobial peptide (SMAP)-29 and human neutrophil peptide (HNP)-1, well-characterized sheep alpha-helical and human alpha-defensin peptides, respectively. Fluorescence-based biochemical assays demonstrated that the ostricacins bound lipopolysaccharides and disrupted both outer and cytoplasmic membrane integrity. The ostricacins' permeabilizing ability was weaker than that of SMAP-29, but stronger than HNP-1. As ostricacins have previously shown the ability to inhibit bacterial growth, these peptides were suggested to be bacteriostatic to Gram-negative bacteria, which are caused by the interaction between the peptides and cytoplasmic targets causing the inhibition of DNA, RNA, and protein synthesis as well as enzymatic activities. These findings indicated promising possibilities for the peptides to be used in the development of therapeutic and topical products.     

Mechanics of running of the ostrich (Struthio camelus)

Ostriches have been filmed running fast in their natural habitat. A female ostrich has been dissected and the principal bones, muscles and tendons in a leg have been measured. It is calculated that stresses up to 240 kN m⁻² and 40 MN m⁻², respectively, act in the digital flexor muscles and their tendons during running. Tensile and compressive stresses up to about 70MNm⁻² and 110 MNm⁻² act in the tibiotarsus. A large proportion of the energy which would otherwise be required for running is probably saved by elastic storage in tendons. Comparisons are made with the legs of flying birds and of antelopes.     

Identification of ostrich and chicken cholecystokinin cDNA and intestinal peptides

The cDNAs encoding the preprohormones of the regulatory peptides cholecystokinin (CCK) and the related gastrin have been identified in a number of vertebrate species. However, from birds only chicken preprogastrin is known. In the present study preproCCK cDNA was identified in two species of birds, ostrich and chicken. In addition, the molecular forms of the bioactive peptides expressed in the small intestine were characterized. Both preproCCKs contain mono basic processing sites for the production of CCK-70 and -8 as seen in turtle and bullfrog. However, compared to these species an unusually large proportion was processed to the small forms CCK-7 and -8 and only minute amounts to larger forms. The encoded preprohormones are very similar to each other and to turtle CCK. Furthermore, they also show a high degree of similarity to the CCKs identified in more distant vertebrates. This confirms that CCK is highly conserved among vertebrates while the structure of gastrin, the other member of the CCK/gastrin family, is considerably more variable.     

In vitro polyploidization of mature ostrich fern sporophytes through rejuvenation

An in vitro method is described for producing ostrich fern (Matteuccia struthiopteris (L.) Todaro) polyploids from mature sporophytes as a possible means of plant improvement in this economically important fern species. The procedure is based on rejuvenating adult sporophytes (2n) to enable the aposporous production of diploid (2n) gametophytes, and then mating the gametophytes to produce tetraploid (4n) sporophytes. The adult sporophytes were rejuvenated by culturing excised shoot tips for a minimum of three months in a liquid medium (Murashige and Skoog salts) under conditions of extreme carbohydrate deprivation (0.01% sucrose). Apospory was induced by culturing leaves excised from the rejuvenated shoots for two months on a semi-solid medium lacking sucrose, resulting in the production of diploid gametophytes. The gametophytes were transferred to fresh medium and grown to sexual maturity for one or two months, then floated on the surface of a liquid medium containing 0.01% sucrose for up to two months to promote opening of the sex organs. Subsequent self-fertilization resulted in the successful production of tetraploid sporophytes in 11 of the 14 diploid clones in which polyploidization was attempted. Tetraploids (4n=156) were confirmed by cytological examination. This method permits polyploidization of mature, fully characterized plants.     

The isolation and partial characterization of precursor forms of ostrich carboxypeptidase

Ostrich carboxypeptidases A and B were recently purified and characterized. The aim of this study was to isolate and purify, and partially characterize in terms of molecular weight, pI, amino acid composition and N-terminal sequencing, the precursor forms of carboxypeptidases from the ostrich pancreas. Inhibition studies with soybean trypsin inhibitor and activation studies with three proteases (bovine trypsin, bovine chymotrypsin and porcine elastase) were performed on crude ostrich acetone powder and the carboxypeptidase A and B activities were determined. SDS-PAGE was carried out after every incubation to monitor the rate and degree of conversion of a M(r) 66K component to procarboxypeptidase and carboxypeptidase A and B. The precursor forms were purified by Toyopearl Super Q and Pharmacia Mono Q chromatography. All three proteases converted the M(r) 66K component to procarboxypeptidases and carboxypeptidases over a set time interval, with carboxypeptidase A and B activities being detected in the acetone powder. Chymotrypsin was the preferred protease since it exhibited a more controlled activation of the procarboxypeptidases. The amino acid composition of procarboxypeptidase A revealed 525 residues. The N-terminal sequence of procarboxypeptidase A showed considerable homology when compared with several other mammalian sequences. M(r) and pI values of 52K and 5.23 were obtained for procarboxypeptidase A, respectively. This study indicated that ostrich procarboxypeptidase A is closely related to other mammalian procarboxypeptidase A molecules in terms of physicochemical properties.